#include<iostream>
#include<vector>
using namespace std;

class Solution {
public:
    int minCostClimbingStairs(vector<int>& cost) {
        vector<int> dp(cost.size() + 1);
        dp[0] = 0;
        dp[1] = 0;
        for(int i = 2; i <= cost.size(); i++){
            dp[i] = min(dp[i - 1] + cost[i - 1], dp[i - 2] + cost[i - 2]);
        }
        return dp[cost.size()];
    }
};

int main()
{
    Solution s;
    int n;
    cin >> n;
    vector<int> cost(n);
    for(int i = 0; i < n; i++)
        cin >> cost[i];
    cout << s.minCostClimbingStairs(cost) << endl;
    return 0;
}